Oxidative dehydrogenation (ODH) has for a long period been a topic on intense academic and industrial interest due to its potential for economically producing olefins. One promising route to oxidative dehydrogenation is by utilizing the advantages provided by microchannel technology. Pioneering work in designing microchannel systems for oxidative dehydrogenation is described in U.S. Published Patent Application No. 2004/0034266 by Brophy et al., and this published application is incorporated herein as if reproduced in full below. Improved catalyst formulations and methods for conducting ODH in microchannels are described in U.S. Published Patent Application No. 20050272965, published Dec. 8, 2005; this published application is also incorporated herein as if reproduced in full below.
Numerous types of conventional apparatus have been proposed for conducting ODH reactions including monoliths, fixed beds and fluidized beds. Lodeng et al. in U.S. Pat. No. 5,997,826 describe a reaction in which relatively narrow, catalyst-free oxygen mixing zones alternate with relatively larger catalyst-containing ODH zones.
Pt and some Pt alloys have long been known as catalysts for some applications in high temperature oxidative dehydrogenation. For example, Font Freide et al. in U.S. Pat. No. 4,940,826 discuss Pt and Pt—Pd catalysts for the oxidative dehydrogenation of ethane, propane and butane. U.S. Pat. Nos. 5,639,929 and 6,846,773 report the use of Pt—Au catalyst particles in fluidized bed reactors, although in the '773 patent it is mentioned that a Pt—Au monolith catalyst could not initiate ethane ODH. Although several patents broadly discuss a broad range of Pt catalysts; recent work have focused on Pt—Sn and Pt—Cu as the best catalysts for ODH. See U.S. Pat. Nos. 6,166,283, 6,365,543, 6,566,573, 6,756,515, and 6,756,340. Indeed, Schmidt et al. (see, for example, U.S. Pat. No. 6,452,061) have warned against Pd or Au alloys with Pt because these alloys are detrimental to the results of the ODH process.